I have created a mutation annotation format (maf)-like text file and need to convert it into a .maf file for further analysis. Is there any way to do this conversion using a software or in R? There doesn't seem to be much information going from a .txt -> .maf. Any help would be greatly appreciated! I'm at a roadblock until I can figure this out.
Your TXT file may already fit the MAF format specification if you have the required columns. You have not indicated the columns that you already have, so, I (and no-one else) can say for definite. Keep in mind that MAF files are plain text, tab-delimited, and have specific column names. The TXT extension itself usually indicates that a file is plain text but says nothing about the structure / arrangement of the data inside.
You can check here whether or not your file is already in the MAF format (see Table 1): Mutation Annotation Format (MAF) Specification
On that same page, see the information under the heading 'MAF file checks'.
Keep further in mind that the MAF format was created as a result of the TCGA project, so, it is tailoured for cancer.